The present invention relates to a thermal transfer recording medium. More particularly, it relates to a thermal transfer recording medium having a structure wherein an ink layer and an adhesive layer are provided on a foundation in this order.
A typical example of the thermal transfer recording medium of this type has a structure wherein a heat-meltable or heat-softening ink layer is provided on a foundation. There is also known a thermal transfer recording medium having a structure wherein an adhesive layer is further provided on the ink layer of the foregoing recording medium.
When materials exhibiting sufficient adhesion to a receptor, for example, a polyester resin having a softening point of about 60.degree. C., or the like, are used as a material for the adhesive layer of the thermal transfer recording medium of the aforesaid structure, many of them show fair adhesiveness at ordinary temperatures. Consequently, when the thermal transfer recording medium is stored in such a state that it is wound in the form of a roll, the adhesive layer adheres to the back surface of the foundation in contact with the adhesive layer (this phenomenon is generally called "blocking"), so that difficulty arises in unwinding and dispensing the recording medium in an image formation device, injuring the stability of the recording medium in traveling and eventually inviting the deterioration of image quality. It is also known to add inorganic particles or a wax to the adhesive layer in order to prevent the blocking. However, the addition of the inorganic particles or wax to the adhesive layer is likely to reduce the adhesion to a receptor, thereby causing decreased scratch resistance or falling-off of print images.
The thermal transfer recording medium wherein the adhesive layer is composed of a wax or a resin having relatively high polarity, for example, polyester resin, polyamide resin, cellulosic resin, phenol resin, acrylic resin, or the like has the problem that it does not exhibit sufficient adhesion to a receptor made of a resin having a relatively low surface tension such as polyethylene or polypropylene.
In view of the foregoing, an object of the present invention is to provide a thermal transfer recording medium which exhibits sufficient adhesion to various receptors and does not cause blocking.
This and other objects of the present invention will become apparent from the description hereinafter.